After a bruising few weeks of sell-offs and volatility, financial markets worldwide perked up this week. But that hasn't stopped Citigroup chief economist Willem Buiter from predicting dark clouds on the economic horizon. In his estimation, the world economy stands a 55 percent chance of entering into recession in the next few years.

To blame, Buiter wrote, is China and other emerging markets whose economies have stumbled as of late. As the world's second-largest economy, China poses a "rapidly rising risk of a cyclical hard landing," Buiter writes. The country's blistering growth has cooled, and Beijing's predicted 7 percent growth rate is likelier to come in at around 4 percent, Buiter wrote. He added that it could slip to 2.5 percent.

And that loss of demand could sting.

China's woes -- punctuated recently by the bursting of a massive domestic equities bubble and repeated currency devaluations -- are reflected in Brazil, Russia and South Africa, whose own economic slowdowns have given investors around the globe pause. These fears were largely to blame for a historic stock market rout on Aug. 24 that left the Dow Jones Industrial Average down 1,000 points early in the day, before closing 588 points in the red.

Though other economists recently have downplayed the risks that a Chinese downturn poses to the global economy, Buiter told CNBC Wednesday morning that China's economy "is now large enough to affect the U.S." The era of global slumps born principally in America, as the 2008 financial crisis was, has ended, Buiter argued. Officials from the International Monetary Fund and European Central Bank have sounded similar alarms.

It's not all bad news, however. Despite China's alarming levels of debt -- loans to households and companies now stand at more than double the country's GDP -- Buiter doesn't see a financial crisis in the works, but a "classic cyclical slowdown," he told CNBC. "It's possible that the U.S. can skate through this unscathed."